In designing a vehicle's rear structure, an automotive designer must take into account a variety of often competing goals and constraints. Exemplary design goals include providing an adequate, if not spacious, rear compartment, providing a spare tire compartment, achieving the desired performance characteristics for the car (e.g., desired dynamic bending and torsional rigidity characteristics), providing mounting structures for vehicle cross-members and floor paneling, and achieving a reasonable level of protection to the vehicle's occupants during a rear collision. At the same time, the designer must also achieve a relatively lightweight structure in order to minimize its impact on the vehicle's MPG or MPGequivalent, and a structure that is easy to fabricate and assemble, thus maintaining low manufacturing cost.
One attempt of at least achieving some of these design goals is disclosed in U.S. Pat. No. 6,834,910, issued 28 Dec. 2004. As disclosed, a Y-shaped rear brace is included in the vehicle's rear structure, the Y-brace helping to achieve the desired level of static and dynamic bending and torsional rigidity while adding minimal weight to the vehicle. In at least one of the disclosed embodiments, the location of the Y-brace leaves an indentation for a spare tire.
U.S. Pat. No. 5,468,018, issued 21 Nov. 1995, discloses a rear torque box assembly that includes two interconnected box members that are mounted between the vehicle's side rails and body side sills. The design of this assembly provides torsional stiffness while providing support for a rear suspension trailing link. An alternate rear torque box design is disclosed in U.S. Pat. No. 5,320,403, issued 14 Jun. 1994.
It is therefore an object of the present invention to provide a simplified vehicle rear torque box structure that is easy to manufacture, lightweight, provides mounts for the rear vehicle structures without the use of additional reinforcements, and achieves the desired torsional and rigidity characteristics.